Challenge

The carcinogenicity of diesel exhaust in humans has remained unclear despite 35 previous studies that investigated lung cancer risk in relation to diesel engine exhaust.

Advance

In 1992, researchers led by Debra T. Silverman, Sc.D., and colleagues at the National Institute for Occupational Safety and Health launched a study designed to clarify the relationship between exposure to diesel engine exhaust and the risk of death from lung cancer. The study is the first to show a statistically significant exposure-response of increasing lung cancer risk associated with increasing exposure to diesel exhaust based on quantitative estimates of workers’ exposure, after adjusting for other lung cancer risk factors including cigarette smoking

Impact

The broad range of diesel exposure in this study allowed researchers to estimate lung cancer risk for heavily exposed workers, as well as those exposed to low levels of diesel exhaust. The new findings are important not just for miners, but also for the 12 million American workers and tens of millions more worldwide who are exposed to diesel exhaust in the workplace and for people who live in cities with high levels of diesel exhaust, the study authors noted.

In June 2012, the International Agency for Research on Cancer (IARC), part of the World Health Organization, classified diesel engine exhaust as carcinogenic to humans (a group 1 carcinogen). The decision was based on an IARC working group’s opinion that the body of evidence supports an association between diesel exhaust exposure and an increased risk of lung cancer. The classification was based on results from several large human studies. The Diesel Exhaust in Miners Study played a pivotal role in the IARC evaluation.